a) Field of the Invention
The present invention relates to a governor provided with a pulley for controlling the speed of a movable body slowly.
b) Background Art
An example of a movable body whose moving speed is to be controlled slowly is a travelers'baggage shelf of an airplane. With reference to FIG. 12, a governor for controlling the moving speed of a baggage shelf will be described hereinbelow. A baggage shelf 100 is pivotally supported by a frame attached to an airplane ceiling (not shown) via an axle 101. The baggage shelf 100 is pivotally movable between the upper storage position as shown by the solid lines and the lower position as shown by dot-dot-dashed lines, and moved downward to the lower position by its weight when a latch mechanism (not shown) is released.
To the baggage shelf 100, one end 103a of a wire (a long member) 103 pulled out from a governor 102 fixed to the frame body is connected. The other end (not shown) of the wire 103 is reeved around a pulley 104 provided for the governor 102. The governor 102 provided with a pulley is disclosed in Japanese Published Unexamined (Kokai) Utility Model Application No. 6325867.
The prior art governor includes a pulley around which a wire is reeved, a speed up gear train for increasing the speed of the pulley when the wire is pulled, and braking means for braking the speed up gear train to control the let out speed of the wire, that is the speed of the movable body. The braking means is compose of a friction member which expands when rotated, and a circumferential wall for applying a brake force to the friction member in contact with the friction member.
When the latch mechanism of the baggage shelf 100 is released at the storage position, the shelf 100 is pivoted down to the lower position as shown by the dot-dot-dashed lines by pulling out the wire 103 from the governor 102 by the weight of the shelf 100. When the wire 103 is being pulled out, the pulley 104 is rotated. In this case, a brake force is applied to the rotating pulley 104 by the braking means via the speed up gear train. That is, immediately after the shelf 100 starts to drop, the shelf 100 is pivoted downward at a relatively high speed to a brake start position a at which the brake is applied. After that, however, the shelf 100 pivots at a relatively slow speed down to the full pivotal position.
The governor provided with a pulley has been explained by taking the case of application to a travelers'shelf of an airplane. Without being limited thereto, the governor of this type can be applied to a movable body (e.g. a pivotal shelf) used in a kitchen, an office room, etc.
The above-mentioned governor has an advantage of being free from oil leakage because no hydraulic device is used. However, since the speed up gear train composed of a plurality of gears of multiple stages is used to increase the rotational speed of the pulley and further to transmit the increased speed to the braking means, there exist problems in that the number of parts is large, the structure is rather complicated, and therefore the cost thereof is high. In addition, since the pivotal speed of the baggage shelf is roughly constant from the time a braking force is applied to when the shelf is completely pivoted open, there exists another problem in that the feeling of the downward motion of the shelf is not preferred. In other words, it is preferred to realize such an brake application process where the shelf is pivoted down at a relatively high speed midway but at a slow speed near the full open position, even when a braking force is applied to the shelf.